A battery is an electronic component that stores electrical energy. Many batteries operate by storing electrical energy in the form of chemical energy using several voltaic cells connected in series by a conductive electrolyte. One half-cell includes an anode and the other half-cell includes a cathode. As the battery operates, a reduction-oxidation (redox) process occurs, causing cations to be reduced at the cathode, while anions are oxidized (removal of electrons) at the anode. During the redox process an electrical potential is created across the terminals of the battery.
Some batteries are configured to be re-charged. During the re-charging process, an electrical potential is applied across the terminals of the battery and the redox process described above is reversed—active material within the battery is oxidized, producing electrons, while the negative material in the battery is reduced, consuming electrons. After charging the battery, a load can be connected across the battery terminals, the original redox process occurs and the load is powered by the chemical energy stored within the battery.
In some cases, batteries can become overcharged resulting in a potentially hazardous condition. For example, in some batteries or cells, overcharge may cause the battery to vent hydrogen (generated by electrolysis of the water in the electrolyte)—a potentially explosive gas. In one specific example, when a lithium polymer cell is overcharged, the internal electrolyte overheats causing pressure to build inside the battery cell. As the battery is overcharged, the temperature and pressure continues to increase until the soft aluminum outer casing perforates causing potentially explosive internal solvent gasses to be vented. If the overcharge is allowed to continue, the solvent gas may ignite, resulting in a significant fire flash lasting approximately one minute. In some cases, however, if the overcharge is discontinued at the point of perforation (venting) there may be no fire event.
There exists a need for a system that does not rely solely on the temperature of a battery to determine if flame retardents should be used on the battery. There further exists a need to remove the source of the temperature rise which is most commonly an overcharge situation.